How to configure which Blender version opens when clicking on a .blend file?
For Windows:
On windows 7 right click on any .blend file and select open with and choose default program . Then use the browse button to navigate where the version you want of the blender program is on your hard drive, and select blender.exe as your default program to open this kind of file. To make the selection permanent check the box that says  always choose the selected program to open this kind of file.

On Windows 10 right click on the file and use choose other app:

Then on the next screen navigate all the way to the bottom and click on look for other app on this PC

On Linux it's basically the same procedure:
Right click on the blend file and select Open with other application

then from there navigate to the folder the blender version you want to use:


On OSX
Ctrl Click on the icon and select open with-&gt;Other and select the blender executable you want to use.